1. Field of the Invention
The present invention relates to an image recording apparatus including a recording head that records an image on a recording medium, and a carriage that carries the recording head and reciprocates in opposite directions intersecting a feeding direction in which the recording medium is fed, and particularly to such an image recording apparatus in which an ink supply tube that supplies an ink to the recording head is connected to the carriage such that the ink supply tube can follow the reciprocation of the carriage.
2. Discussion of Related Art
As an image recording device that ejects, based on an input signal, droplets of ink to record an image on a recording medium, there is known such a device that includes a recording head having an actuator (e.g., a piezoelectric element, an electrostriction element, or a heating element), and supplies ink to the actuator so that when the actuator is deformed or heated based on an input signal, the ink is locally pressed or vaporized to eject droplets of the ink.
For example, an image recording device that is so-called a serial printer includes a carriage that reciprocates in opposite directions perpendicular to a direction of feeding of a recording medium, and a recording head that is mounted on the carriage. Each time the recording medium is fed by an incremental amount corresponding to one line, the carriage reciprocates to record the line. Ink is supplied to the recording head from an ink cartridge separate from the carriage, via a flexible ink supply tube that is connected to the recording head mounted on the carriage. The ink supply tube is long enough to follow the reciprocation of the carriage, and is provided between the ink cartridge and the carriage such that the ink supply tube is flexed to form a generally U-shaped curved portion. This image recording device is disclosed by any of Japanese Patent Application Publications Nos. 10-217496, 2003-11340, 2005-35033, 63-154354, and 2005-88524.
FIG. 23 schematically shows a conventional image recording device including a carriage 90 and an ink tube 91. The carriage 90 reciprocates in opposite directions (i.e., in leftward and rightward directions in the figure) perpendicular to a direction of feeding of a recording sheet. When the carriage 90 reciprocates, a recording head (not shown) mounted on the carriage 90 ejects droplets of ink to record an image on the recording sheet. The ink tube 91 that is led from an ink cartridge is connected to the recording head mounted on the carriage 90, such that a midway portion 92 of the ink tube 91 that is located between the ink cartridge and the carriage 90 is fixed to a portion (e.g., a frame) of a housing of the image recording device and an intermediate portion between the midway portion 92 and the carriage 90 is not fixed to any portions. Therefore, the intermediate portion of the ink tube 91 can change its shape. Although not shown in FIG. 23, the carriage 90 is moved while being driven by, e.g., a belt driving device, and is supported by one or more guide members such as a guide shaft(s) or a guide rail(s) that extend(s) in a direction of movement of the carriage 90.
As shown in FIG. 23, the ink tube 91 is led from the carriage 90 in a horizontal direction, and is flexed to have a generally U-shaped curved configuration in its plan view. When the carriage 90 reciprocates, the ink tube 91 follows the carriage 90 while a center of the U-shaped curved portion of the ink tube 91 moves. The ink tube 91 is straight in its initial shape, but when an external force is applied to the tube 91, the tube 91 is flexed. The ink tube 91 has such a flexibility that if the external force is removed from the tube 91, the tube 91 is returned to its initial, straight shape: Therefore, as shown in FIG. 23, the ink tube 91 can change its shape such that when the carriage 90 is moved in a rightward direction, a diameter of the U-shaped curved portion of the ink tube 91 increases and, when the carriage 90 is moved in a leftward direction, the diameter of the U-shaped curved portion decreases.
Meanwhile, a flexible, electrically conductive cable that is so-called a flat cable is connected, at one end thereof, to the carriage 90 so as to control the recording head. The other end of the flat cable is connected to, e.g., a main substrate. Like the above-described ink tube 91, the flat cable is led from the carriage 90, and follows the reciprocation of the carriage 90 while forming a generally U-shaped curved portion. This image recording device is disclosed by, e.g., Japanese Patent Application Publication No. 6-320835.
As explained above, the flat cable and the ink tube have such flexibilities that assure that those elements can follow the reciprocation of the carriage while changing the diameters and/or positions of the U-shaped curved portions thereof. Accordingly, the respective intermediate portions of the flat cable and the ink tube, located between the carriage and the respective midway portions of those elements fixed to the housing of the image recording device, may more or less sag downward. In particular, in the case where the flat cable and the ink tube are led horizontally from the carriage, there is a strong tendency that those elements sag downward due to their self weights and/or the weight of the ink. In addition, in a full-color-image recording device, a plurality of sorts of inks corresponding to a plurality of colors are supplied to a recording head mounted on a carriage via a plurality of ink supply tubes, respectively. Although the ink supply tubes follow the reciprocation of the carriage while individually changing their shapes, the changing of those shapes may be out of order, i.e., random.
In the case where a sufficiently broad space cannot be provided around a flat cable and/or an ink supply tube, in view of the need to reduce a height and/or an overall size of an image recording device, reciprocation of a carriage may result in enlarging respective curved portions of the flat cable and the ink tube so that the enlarged curved portions may be brought into contact with one or more peripheral members and even be damaged by the same. The damaging of the flat cable may cause breakage of one or more electrically conductive lines contained therein; and the damaging of the ink supply tube may cause leakage of ink. In addition, when the flat cable and the ink tube are contacted with the peripheral members, a load may be applied to the carriage so that the speed of movement of the carriage may be made unstable and accordingly a quality of images recorded by the recording head may be lowered.